Hussain M, Ichihara S, Mizushima S
J Biol Chem. 1980 Apr 25;255(8):3707-12.
The protein accumulated in the cell envelope of Escherichia coli treated with globomycin was identified as the precursor of the outer membrane lipoprotein. The prolipoprotein was almost exclusively localized in the cytoplasmic membrane. The prolipoprotein could be immunoprecipitated with antilipoprotein immunoglobulin and could be chased to the lipoprotein in both in vivo and in vitro. Globomycin inhibited the chase. The prolipoprotein contained glycerol and fatty acid residues, whereas no free sulfhydryl group was detected in it. From these results, it is concluded that the prolipoprotein possesses a glyceride which is covalently bound to the cysteine residue in the peptide as the lipoprotein does and that the removal of signal peptide takes place after the modification. The inhibition of bacterial growth with increasing concentrations of globomycin was accompanied by a gradual increase in the accumulation of the prolipoprotein. Furthermore, growth of the lipoprotein-negative mutant was highly resistant to globomycin. These results strongly indicate that the accumulation of the prolipoprotein in the cytoplasmic membrane causes the death of cells.
用球霉素处理的大肠杆菌细胞包膜中积累的蛋白质被鉴定为外膜脂蛋白的前体。前脂蛋白几乎完全定位于细胞质膜中。前脂蛋白可用抗脂蛋白免疫球蛋白进行免疫沉淀，并且在体内和体外均可追踪到脂蛋白。球霉素抑制了这种追踪过程。前脂蛋白含有甘油和脂肪酸残基，而在其中未检测到游离巯基。从这些结果可以得出结论，前脂蛋白具有一种甘油酯，该甘油酯与脂蛋白一样共价结合于肽中的半胱氨酸残基，并且信号肽的去除发生在修饰之后。随着球霉素浓度的增加，细菌生长受到抑制，同时前脂蛋白的积累逐渐增加。此外，脂蛋白阴性突变体的生长对球霉素具有高度抗性。这些结果强烈表明，前脂蛋白在细胞质膜中的积累导致细胞死亡。
